Fungal polyketides are a family of secondary metabolites synthesized by molds from acetate via the acetate-polymalonate pathway. Among which aflatoxins, sterigmatocystin, zearalenone, patulin, and ochratoxins have been identified as widespred mycotoxins of definite food safety significance. In this proposed research, the biosynthetic mechanisms of aflatoxins are used as a model to elucidate biochemical events involved in the synthesis of fungal polyketides and to develop means by which mycotoxin synthesis can be inhibited or diverted to synthesis of less harmful compounds. The chicken embryo and Salmonella-microsomal tests are used as routine bioassays to screen toxic and potentially carcinogenic fungal polyketides that are related with the known major mycotoxins. The overall objective is to expedite discovery and control of toxic fungal polyketides as foodborne mycotoxins. BIBLIOGRAPHIC REFERENCES: Hsieh, D. P. H. and Yang, S.L. Preparation of C 14 C-sterigmatocystin in liquid media. Appl. Microbiol. 29: 17-20, 1975. Fitzell, D.L., and Hsieh, D. P. and Reece, C. A., and Seiber, J.N. Preparation of acetic-1-C 13 and Malonic-1-C 13 acids of biosynthetic studies. J. Labelled Compounds. 11:135-139, 1975.